The aim of the CUTE project is to study the structure, thermodynamic and electrochemical properties of alkaline nanoparticles confined into nanopores of large surface area host materials (i.e. mesoporous carbons or silica gels).
The practical use of alkali metals as reagents for reductive organic chemistry or as negative electrodes in secondary non-aqueous batteries has been limited owing to safety considerations and immense difficulty in industrial scale-up. Milder alternatives in organic reduction chemistry rely on nanoconfined alkali metals (i.e. Na or Na/K alloys) impregnated into large surface area silica. Very recently, inspired by the commercial K-Na-silica composite, K-Na alloys and Li have been absorbed by melt impregnation onto carbon papers. These composite materials have been demonstrated as promising negative electrodes in sodium and lithium non-aqueous rechargeable batteries with mitigated dendrite growth upon cycling.
Here our goal is to tackle the synthesis, physico-chemical characterization and electrochemical tests in lithium and sodium non-aqueous secondary galvanic cells of nanocomposite materials constituted by alkali-metals nanoparticles hosted into large surface area materials like silica gels and mesoporous carbons. The aim is to prepare alkaline-based nanocomposites stable in air thus opening the door for practical exploitation with industrial-suitable scale-up. To this aim the CUTE project will last 12 months and will develop (4) different research activities (Preparation of (Li,Na,K)/SiO2 and (Li,Na,K)/carbon nanocomposites; Investigation of the stability in air, structure, morphology and bonding properties of the nanocomposite materials; Analysis of the thermodynamic properties; Evaluation of the electrochemical properties and performances non-aqueous Li/Na galvanic cells) carried out by a Sapienza-CNR joint team constituted by (4) permanent Sapienza research staff, (2) permanent CNR researchers and (1) non-permanent post-doc.
Nanoconfined alkaline metals (i.e. Na or Na/K alloys) impregnated into large surface area silica or carbons [1-3] are promising materials for application as reducing reagents in organic chemistry or as negative electrode materials in secondary non-aqueous batteries. In the case of the silica-composites, these materials have the same reducing power as the parent alkali metals and are obtained by intercalation of up to 40 wt % of liquid alkali metals into the nanopores of meso-structures. These materials are nonpyrophoric and have good stability in dry air, making them easy to handle and easing storage concerns. These aspects of the alkali metal silica gel (materials make them ideal candidates as reactants for large-scale hydrogen production and organic reduction chemistry [1,4-5]. However, despite their promise, the precise nature, structure, morphology, chemical bonding, physico-chemical and electrochemical properties (e.g. electronic and ionic conductivity, thermal stability, electrochemical activity) of these nanocomposite metal-silica materials have not clearly understood and investigated, yet. This lack of knowledge occurs also for the parent K-Na alloys and Li carbon nanocomposites. These materials have been demonstrated as promising negative electrodes in sodium and lithium non-aqueous rechargeable batteries with mitigated dendrite growth upon cycling [2-3]. However, also in these success cases, the identification of valuable functional materials for batteries has been obtained through a try-and-fail approach rather than based onto a solid understanding of the fundaments of these nanoconfined materials. In fact, neither the structure nor the thermodynamics of these nanoconfined alkaline-based nanocomposites have been clarified or even scratched.
The aim of the CUTE project is to study the structure, thermodynamic and electrochemical properties of alkaline nanoparticles confined into nanopores of large surface area host materials (i.e. mesoporous carbons or silica gels). This major goal will be tackled through the preparation, phyco-chemical characterization and electrochemical tests in lithium and sodium non-aqueous secondary galvanic cells of nanocomposite materials constituted by alkali-metals nanoparticles hosted into large surface area materials like silica gels and mesoporous carbons.
The goal is to develop a comprehensive description of the fundamental properties of selected samples of these nanocomposite materials constituted by nanoparticles of alkaline metals impregnated into the mesoporous structure of an open host matrix, either silica or carbon-based. This challenge has never been tackled so far although the remarkable available examples of technological relevance of these nano-composite materials [1-5]. In this view the CUTE project will break the ice and will develop a basic knowledge suitable for further development both from the side of the fundamental investigation in materials science and from the applied exploitation of the experimental results.
[1] J.L.Dye et al. Journal of the American Chemical Society 127 (2005) 9338; [2] Z.Liang et al. Proceedings of the National Academy of Sciences (PNAS) 15 (2016) 113; [3] L.Xue et al. Advanced Materials 28 (2016) 9608; [4] ] J.L.Dye et al. Chemistry of Materials 23 (2011) 2388; [5] M.Shatnawi et al. Journal of the American Chemical Society 129 (2007) 1386;